Means for controlling induction electricity meters



Na 5, 1929. w. BEUSCH 1,734,110

MEANS FOR CONTROLLING INDUCTION ELECTRICITY METERS Filed Jan. 15 1927 Patented Nov. 5, 1929 UNETEQ STATE earner orerca WILLI BEUSCH, OF ZUG, SWITZERLAND, ASSIGIJOR T0 LANDIS & GYR, A."G"-, A LIMETED JGINT-STOCK COMPANY, OF SWITZERLAND IVIEAN'S FOR CONTROLLING INDUCTIQI'J"ELECTRICITY METERS Application filed January 15, 1927, Serial No. 161,327, and in Switzerland January 29, 1926.-

The invention relates to induction electricity meters and more particularly to new and useful corrective or compensating devices for maintaining substantially correct readings of the meter notwithstanding variations in temperatures.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawing, referred .to herein and constituting a part hereof, illustrates one embodiment of the invention, and together with the description, serves to eX- plain the principles of the invention.

The drawing is a diagrammatic elevation of the driving system of an induction meter embodying one form of the invention.

In practice nearly all induction meters show plus errors with increases in temperature, and vice versa, at least at unity power factor. It is usually stated that the meters have a positive temperature coefiicient, and this coefficient is the mean additional error per degree centigrade between two definite temperatures, as for example, between 20 degrees and degrees.

These temperature errors are caused primarily, or at least in part, by the action of the brake magnet, as its flux decreases with a rise in temperature, and increases when the tem perature drops. The meter driving system also acts, under temperature variations, in partly causing these errors.

Previous efforts and means for correcting or compensating for these errors have been directed to neutralizing the temperature reactions of the brake magnet.

The present invention is directed to new and useful means for counteracting the errors, or that part of the error in the meter registrations due to the influences of tem- 59 perature variations on the driving system.

In most induction'meters the temperature coefficient varies with changes in the power factor. That is, at a fifty per cent power factor the temperature coefficient is smaller than at unity-power factor due to increase in the ohmic resistance in thepressure coil.

If the temperature coefficient at unity power factor is being decreased through relative increase in the braking action due to rise in temperature, the same result is caused at fifty per cent power factor, and if a total compensation is 'efiected for such change in the braking action at unity power factor, this compensation will cause a negative error at fifty per cent power factor due to increase in the resistance in the pressure coil The present invention has in view the neutralization of variations in the action of the driving system through variations in the resistance of the pressure coil due to temperature changes, and also the compensation of variations in the brake magnet action, thereby eliminating in a high degree the errors due to temperature changes. More in detail by my invention, the changes in resistance in the pressure coil and the changes of the braking force of the brake magnet due to variations in temperature, are compensated for by effecting changes in the torque so as to retain substantially proportional the relation of the torque to the brake action of the magnet under all power factor conditions.

By my invention. an. additional magnetic circuit is provided in the air gap of the magnetic shunt circuit. the flux thereofchanging proportionally to changes in temperature. Its resistance is rendered changeable by the use of a bi-metallic strip or member, the metals of which have difierent coefficients of expansion, whereby the air gap is increased or diminished with the changes in temperature. The resultant variations in this additional magnetic circuit will thus correspondingly vary the action of the driving flux on the meterdlscs.

By thisv additional regulating circuit the phase displacement, which would otherwise be affected by the change in the ohmic resistance of the pressure coil is maintained substantially undisturbed. There is thus effected a compensation for the temperature disturbances in induction meters.

The single figure of drawing shows diagrammatically an exemplary specific embodiment of the invention, but it will be 1mderstoodthat various changes may be made therein as may be found desirable or efficient. In said exemplification, the driving core 1 carries a pressure coil 2 and current coils 3. The core 1 is formed with an extension 6 with an air gap 4; between the end thereof and the middle part of core 1.

The embodied means for varying the width of air gap 4 comprises a strip 5, consisting of two attached strips of metal having different co-efiicients of expansion, any of the known suitable metals being used.

7 This compound strip 5 is mounted upon the I end of the part 6 of the core. The relative width of the gap at 4 and 5 will, of course, be correctly proportioned for the best and most eflicient operation of the device. Any usual or suitable device for Varying the phase angle may also be used in the gap 41.

At normal temperatures, the strip '5 will bepreferably parallel to the core 1, as shown in the drawing, when it is inactive with refer ence to producing a magnetic shunt circuit. With a :rise in temperature, the strip 5 will move toward the core 1, and thereby will establish a magnetic shunt circuit, across the gap to the adjacent part of core 1. Thus the driving flux is decreased, 'and the resultant corrective agencies are created, as already fully described, whereby the errors arising from changes in the ohmicresistance of the pressure coil and in the brake magnet action, due to variationsin'temperature are neutralized. v

It will be understood that the structure and manner of use of a particular embodi ment may be varied from the present dis closure without departing from the prin ciples of the invention andwithout sacrificing itschief advantages.

What I claim, is:

1. In combination in an induction electricity; meter a pressure electr'o-magnetic coil and core having a magnetic shunt circuit with an air gap and a bimetallic strip movable by temperature variations to modify the magnetic flux at theair gap. 1 p '2. In combination a series coil and core, a pressure coil and core, said corebeing formed to provide a shunt circuit having an air gap, and a bimetallic member vat the, 1

air gap, and movable by'temperature changes to vary the magnetic fiuxin the shunt circuit.

In testimony whereof, I have signed my name to c this specification.

, WILL1 BEUSCH. 

